Publication Date

Spring 2017

Advisor(s) - Committee Chair

Jason Polk (Director), Nahid Gani, Thorsteinn Thorsteinsson

Degree Program

Department of Geography and Geology

Degree Type

Master of Science

Abstract

A detailed comparative geochemical characterization of three different types of Iceland glacial systems was conducted during June, August, and October, 2016. The study was carried out at a total of 11 outlet glacier rivers flowing from the icecaps Vatnajökull, Eyjafjallajökull, and Mýrdalsjökull. A total of 75 grab samples were collected (25 for each sampling period). The hydrogeochemical variations of Icelandic glacial meltwater are influenced by volcanic activity, temporal changes, and geographical location, which differed between the sampling sites within the glaciers and icecaps. Lower pH range, and comparatively higher and variable specific conductivity, SO4, S and F is linked to higher volcanic influences, including residuals from the 2010 eruption at Eyjafjallajökull (located above a tectonic plate boundary zone). High concentrations of Al and Fe were found at Kötlujökull and Kvíárjökull, both of which are close to active volcanic zones. Changes in hydrogeochemistry of the meltwater caused by volcanic activity may be used to forecast eruptions and jökulhlaups; however, given the variability of Icelandic meltwater chemistry, high-resolution monitoring should be done in order to determine a precursor threshold for an volcanic event, as the chemical composition of one jökulhlaup could be within normal range for a different glacier.

TSS concentrations depicted high spatial and temporal variation as the highest and lowest values of TSS drained from the same glacier. Hydrogeochemical weathering is driven by Na-HCO3 and Ca-HCO3 dissolution. Concentrations of ions varied with respect to their geographic location, as specific conductivity increase distance downstream from glaciers, proglacial lagoons, and river reaches. Ca, Mg, K, Na, and HCO3 increased from 1984 to 2016 for Fjallsjökull, which may be from an increased weathering rate, due to temperature, CO2 increase, and increased erosion beneath glaciers under a changing climate.

This study of hydrogeochemical variation in Icelandic glaciers complements the database of physical and chemical compositions of understudied glaciers. The hydrogeochemical variations of Icelandic glacial meltwater throughout a diverse sample of glaciers and their respective icecaps are related to internal and external factors, and their diversity indicates a much more complex set of processes underway at the different icecaps and their respective glaciers.

Disciplines

Geology | Geophysics and Seismology | Glaciology | Oceanography and Atmospheric Sciences and Meteorology | Other Oceanography and Atmospheric Sciences and Meteorology